Crops need to be protected against a broad range of diseases and pests. Flowers can be important pathways of plant disease infection or sites of pest occurrence. The pathogen infects them under favorable conditions, and progressively colonizes other tissues or fruits. Disease symptoms become visible when infected tissues ripen, senesce or die, as for example in the case of Botrytis cinerea. Effective disease and pest control depends both on the use of suitable crop protection products, either chemical or biological (microbial or microbial agents), and on the methods and strategies for introducing, promoting and maintaining the antagonist in the crop (Sutton and Peng, Annual Review of Phytopathology, 1993, 31, pg. 473-493).
The use of microbiological antagonist preparations against flower-borne diseases and pests could be particularly effective if dissemination of the antagonist occurs directly to the flower parts during bloom (Peng and Sutton, Canadian Journal of Plant Pathology, 1991, 13, pg. 247-257). Pronubial insects are known to deliver pollen, fungi and bacteria (Dag et al., Journal of Apicultural Research, 2000, 39, Pg. 117-123). Hence, while performing their pollination service, pronubial insects might also serve as carriers of antagonistic agents, providing potential disease and pest control in addition to pollination services (Sutton and Peng, Annual Review of Phytopathology, 1993, 31, pg. 473-493; Sutton, Advances in Plant Pathology, 1995, 11, 171-188).
Worldwide over 500,000 colonies of B. terrestris (L.) are purchased annually for pollination service on various crops, predominantly on tomatoes. In addition to pollination and indirect disease control, these pronubial insects may also perform an active role in preventing disease or pest control by conveying for example microbiological preparations directly onto flowers or other plant parts. This requires that the bees themselves are previously loaded with propagules of the antagonist (Sutton and Peng, Annual Review of Phytopathology, 1993, 31, pg. 473-493). For the latter a dispenser can be mounted on the exit of the beehive. Existing dispenser such as the side-by-side passageway dispenser (SSP) and the overlapping passageway dispenser (OP) have certain drawbacks in loading the bees.
The SSP-dispenser showed several functional limits, as evidenced by the absence of antagonistic propagules on most of the captured and analyzed bees. Inoculum density on bumblebees was also rather low. The SSP-dispenser was also not efficient in separating outgoing and incoming bees: many bees exited the colony box through the darkened straight passageway thus eluding the powder preparation, whereas others crawled through the zigzag passageway, but walked along the side walls. Furthermore the bees promptly smeared the zigzag passageway with their liquid excrements which, once kneaded with the antagonistic powder preparation, caused the latter to lose its consistency making it no longer suitable for bee loading (Maccagnani B. et al., 2005, Bulletin of Insectology 58(1): 3-8)
With the OP dispenser only a limited amount of propagules of the antagonist can be loaded in the lower exit passage and the loading of the bees leaving the hives quickly diminishes. A further disadvantage of the OP-dispenser is the different dimensions of the upper and lower passageway. The upper passageway is broader and higher compared to the lower passageway, as a consequence and given the range in size of bumblebees in a hive, some of the larger bees may leave the hive through the upper passageway of the OP-dispenser and get stuck in the narrower lower passageway. Also, the difference in floor level between the upper and the lower passageway has a negative effect on light entering the exit hole of the hive.
In addition, for both the SSP-dispenser and the OP-dispenser, the inoculum density on flowers and the percentage of colonized flowers were significantly lower than in comparable spray treatment (Maccagnani B. et al., 2005, Bulletin of Insectology 58(1): 3-8). Also, both the SSP and OP dispenser are at the exterior of the beehive, and accordingly sensitive to changes in temperature. For example fully exposed in a greenhouse the temperature increase within the dispenser may not only be detrimental to the control agent but also prevents the bees from leaving the hive.
It is accordingly a general object of the invention to provide a beehive dispenser to overcome the problems mentioned hereinbefore. As provided in more detail hereinafter, the beehive disseminator of the present invention assures a unidirectional exit passage of the bees through the dispenser, thereby preventing bees from entering through the exit (i.e. from entering through the dispenser). An independent and again unidirectional entry pathway is realized through a second chamber, thereby preventing bees from leaving the hive through the entrance. In a particular embodiment the exit and entrance are integrated into one visual unit, contributing to a swift entry by returning bees. Furthermore, the dispenser has a high loading capacity for the agent to be disseminated, it prevents that the bees clear a path in the product, which would prevent effective loading, and thus provides an optimal loading of the bees with a short passage time. The dispenser can be filled through perforation in the top of the chamber. Finally, it can be integrated within a hive to benefit from the internal temperature control. It can be made accessible through a removable top, a sliding mechanism or other means.